The term "diffuser" is used to designate those devices which, in air conditioning systems, are employed for the purpose of regulating flow of air, which may be heated air or cooled air, from air conditioning ducting into a room.
Various conditions occur in an air conditioned room depending on whether the outside temperature is above that at which the room is to be maintained or below that at which the room is to be maintained.
In "Summer" conditions cooled air is fed from the air conditioning plant to the diffuser. If the room temperature is below that at which it is desired to maintain it, because cooled air has previously been fed in, then the diffuser must remain closed to prevent further cooled air entering the room.
As the room heats up a room temperature sensing element must detect this and open the diffuser to allow more cooled air into the room. The diffuser thus opens and closes as the room temperature varies.
In "Winter" conditions heated air is fed to the diffuser. If the room is above the requisite temperature, because heated air has previously been fed into the room, the diffuser must remain closed to prevent further heated air entering. As the room cools down, the room temperature sensing element must detect this and open the diffuser to allow more heated air in. The diffuser consequently opens and closes as the room temperature varies.
In the specification of our South African patent 96/4791 (U.S. Pat. No. 5,647,532 and Australian Patent No. 700908) there is disclosed a diffuser which has a single room temperature sensing element which closes a diffuser when the room is too cold (in Summer conditions) and close the diffuser when the room is too hot (in Winter conditions). This avoids the use of complex constructions involving two or more room temperature sensing elements.